Background and Aim : Chronic non-specific low back pain is one of the important health problem in military and different factors have been reported in its emergence. The aim of this study is to determine the association between low back pain and education level, Body Mass Index (BMI), exercise, smoking status ,work status and bad postures in military men.

Materials and Methods : In this non-experimental case-control study, 92 subjects (mean age= 29.16 year, SD= 8.55 year) with chronic non-specific low back pain and 93 subjects (mean age= 26.80 year, SD=9.22 year) without low back pain were selected by simple non-probability method from military centers in Tehran. Evaluation tools of this study included a self-administrated questionnaire, weighting scale and metal tape measure.

Results : According to the results of bivariate logistic regression, risk factors of exercise (P= 0.003), smoking status (P= 0.042), grade of BMI (P= 0.034), bad posture grades including heavy objects lifting movements (P= 0.007), bending movements (P= 0.003), rotating movements from the lumbar (P= 0.011), carrying bulky objects (P= 0.034), carrying heavy objects (P= 0.05) and working in squatting position (P= 0.005) had a significant association with low back pain. Job status (P= 0.999), education level (P= 0.056) and bad postures grades movements like wringing clothes (P= 0.958) had not a significant association with low back pain.

Conclusion : Doing regular exercise and having normal BMI decrease the risk of suffering from low back pain in the military while smoking and doing injurious physical activities during work (lifting heavy objects, bending movements and rotating from the lumbar, carrying bulky and heavy objects, and working in squatting position for a long time) increase the risk of suffering from low back pain.

Key Words : Chronic non-specific low back pain, Military forces, Biomechanical risk factors, Exercise

Background and Aim: One of the main causes of chronic non-specific low back pain is inappropriate working conditions, high repetition of one activity or work heaviness. An appropriate, accurate, inexpensive and easy assessment tools is necessary for measuring intensity of exposure to injurious  work activities, Identify individuals at risk and using appropriate treatment. The aim of this study is to compare the single-item Borg scale with JRPD scale to identify individuals at risk of exposure to injurious work activities in chronic non-specific LBP.

Materials and Methods: In this cross-sectional survey study, 92 subjects with non-specific low back pain by mean age of 29.16 (SD= ± 8.55) years and 93 healthy subjects by mean age of 26.80 (SD= ± 9.17) years and matched of work time, age and type of service with subjects with non-specific low back pain were selected by simple non-probability method. Single-item Borg scale and JRPD scale were used to assess the intensity of injurious work activities.

Results: Considering JRPD scale as a criterion scale, the sensitivity rate of 82% and specificity rate of 28% was obtained for single-item Borg scale at the moderate threshold. While the severe threshold for this scale, sensitivity and specificity rate were 25% and 85%, respectively. Also, the results showed that both single-item Borg scale and JRPD scale has significant ability to classify subjects with non-specific low back pain which are exposed or not exposed to injurious work ability (P<0.001). 

Conclusion: The single-item Borg scale has high sensitivity and low specificity at the moderate threshold and above and high specificity and low sensitivity at severe threshold to identify individuals Exposed to injurious work activities in military with chronic non-specific LBP.

Keywords: Injurious work activities, Non-specific LBP, Single-item Borg scale, JRPD scale

Background and Aim: Fractal dimension (FD) as a measure of system complexity and a chaos and nonlinear dynamics tool has appeared successful in distinguishing subjects with different specifications such as proficiency level. The purpose of this research was to evaluate the capability of FD analysis of postural stability in distinguishing elite Wushu sportsman for dispatching to various competitions.

Materials and Methods: Eight elite and eight non-elite Wushu sportsmen from Talou section participated in this research and performed a difficult balance motion called “backward balance”. Center of pressure (COP) traces were recorded and Higuchi algorithm has been used to obtain fractal dimension of COP displacement time series. Average of FD of two groups were compared with an unpaired t-test.

Results: In both directions of anterio-posterior (AP) and medio-lateral (ML), average values of FD in elite group were significantly more than non-elite group (p<0.05). Subsequently, implementing a receiver operating characteristic (ROC) analysis indicated that FD analysis method performance is very good in AP direction (Area under the curve or AUC=0.938) and good enough in ML direction (AUC=0.668).

Conclusions: Postural control system acts more complex in elite group because of their more proficiency. FD analysis of COP time series could help coaches in choosing elite Wushu sportsman even among a group of skilled Wushu sportsmen. 

Keywords: Wushu, Postural stability, Fractal dimension, Receiver operating characteristic (ROC), Center of pressure (COP)